Lock bolts are commonly used to fasten two or more structures together. Typically, a threaded lock bolt with a head and a threaded tail section is inserted through holes in the two or more structures, and a collar is swaged onto the threaded tail section using a tool, such as a pneumatic gun. The structures are retained between the head and the collar.
Often, it may be required to remove collars from lock bolts in order to rework the joint, or for other reasons. There are several tools and methods for removing lock bolt collars.
Typically, a chisel is selected having a notch sized for the lock bolt. The chisel has an angled head which can be laid adjacent the joint surface from which the lock bolt extends. The angle of the head allows the head of the chisel to be flat against the joint surface while an opposing end displaced above the joint surface is impacted with a hammer. Upon impact, the lock bolt is knocked off by the head of the chisel. This method is dependent on the skill of the technician, and requires a certain degree of accuracy in placement and impacting of the chisel.
In another method, a nose assembly with a cutting anvil is used to shear a collar off of a lock bolt. The nose assembly may be used with a pneumatically actuated pull-gun, such as those available from Alcoa Inc., of New York, N.Y. The nose assembly grips and pulls the lock bolt such that a pair of cutters is brought against the collar to shear the collar. This method suffers from a difficulty in use. The first attempt to shear the collar is often unsuccessful, requiring the technician to rotate the tool by 90 degrees to attempt another cut. Further, in cases where the lock bolt is being removed because the bolt is too short, this tool may cause the top part of the collar to fold over the top of the bolt, making removal with the cutting tool impossible.
Thus it would be beneficial to provide a tool for easily removing lock bolt collars without providing any risk of damaging any underlying structure. It would further be beneficial to provide a tool which can be used with existing tools, such as pneumatic guns.